Alkali silicate glass based coating and method for applying

ABSTRACT

A coating for reducing interaction between a surface and the environment around the surface includes an alkali silicate glass material configured to protect the surface from environmental corrosion due to water or moisture. The alkali silicate glass material is doped with a first element to affect various forms of radiation passing through the coating. The electromagnetic radiation is at least one of ultraviolet, x-ray, atomic (gamma, alpha, beta), and electromagnetic or radio wave radiation. The coating may also be used to protect a solar cell from the environment and UV rays while retransmitting received light as usable light for conversion into electrical energy. The coating may also be used to prevent whisker formation in metal finishes of tin, cadmium, zinc, etc.

CROSS-REFERENCE OF RELATED APPLICATIONS

This application is a continuation-in-part and claims priority to U.S.patent application Ser. No. 11/508,782, filed Aug. 23, 2006, U.S. patentapplication Ser. No. 11/784,158, filed on Apr. 5, 2007, U.S. patentapplication Ser. No. 11/732,982, filed on Apr. 5, 2007, U.S. patentapplication Ser. No. 11/732,981, filed on Apr. 5, 2007, U.S. patentapplication Ser. No. 11/784,932, filed on Apr. 10, 2007, U.S. patentapplication Ser. No. 11/959,225, filed on Dec. 18, 2007, U.S.application Ser. No. 12/116,126, filed on May 6, 2008, PCT ApplicationNo. PCT/US2008/074224, filed on Aug. 25, 2008, and PCT Application No.PCT/US2008/075591, filed on Sep. 8, 2008, the entire disclosures ofwhich are incorporated herein by reference.

BACKGROUND

Many conventional products, including but not limited tomicroelectronics components, often include a wide variety of coatingmaterials. These coating materials are used in an attempt enhanceperformance of the product or increase product reliability. Coatings areoften used to correct for a known deficiency within the product itself.For example, a thermal coating can be added to help dissipate heat froma specific area of a product to prevent it from overheating during use.In another example, a protective coating may be used to enhance thereliability or manufacturability (e.g., processing windows) of theproduct itself.

These coatings may be organic or inorganic materials. Conventionalorganic coatings absorb moisture, ultraviolet (UV) radiation, etc.Moisture can degrade the coatings and/or the material interfaces theyconnect through chemical decomposition, material expansion, etc. Otherfactors such as elevated temperature, ozone, ultraviolet light, etc. canalso degrade organic coating materials. In addition, organic-basedcoatings conventionally have coefficients of thermal expansion on theorder of 100 ppm/degrees Celsius, which can lead to adhesion and/orcohesion failures when products are subjected to temperature variations.These types of degradation of the coating or device can limitsuitability for use in harsh environments and can lead to failuresduring the operational lifetime of the devices. Application ofconventional inorganic coatings may require expensive and/or high-stressenvironments, such as chemical vapor deposition, or very high processingtemperatures.

Further, circuits are conventionally mounted to circuit boards and othersubstrates using soldered joints. Due to concerns with disposal oflead-based solders, the solder may often be a lead-free solder.Lead-free assemblies often contain components that have a surface finishof electroplated tin, which may have a tendency to develop “whiskers” orfilaments that grow out of tin. Such whiskers can cause electricalshorting if the filaments extend to other metal surfaces or canundesirably coat and adhere to adjacent surfaces. In addition toelectronic substrates that use tin surface finishes, other metalsurfaces often have metal coatings of materials such as tin, cadmium, orzinc that can also produce similar whisker filaments.

In various devices such as a magnetic resonance imaging devices ornuclear magnetic resonance devices, the device may be liquid cooled. Theliquid coolant is typically high purity deionized water and must remainhighly pure and non-conductive in order to prevent deterioration of thereadings made by the device. Corrosion of the coolant system by thecoolant liquid can lead to a decrease in the purity of the coolingliquid and subsequent increase in conductivity and degradation of deviceperformance.

Therefore, a need exists for a material that can coat surfaces in areliable manner and that is not susceptible to harsh environments. Aneed also exists for a material for coating a surface that is capable ofproviding protection from moisture as well as from breakdown by variousforms of radiation (such as UV). A need also exists for a material ormethod for coating surfaces with finishes of materials such as tin,cadmium, zinc, etc. so they do not whisker. A need also exists for amaterial that will prevent the internal corrosion of liquid coolingsystems and maintain a high level of cooling fluid purity andresistivity within it. A need also exists for a material that can beprocessed and cured at temperatures less than 200 degrees Celsius.

SUMMARY

One embodiment of the disclosure relates to an electronic assembly. Theelectronic assembly includes an electronic device mounted on a substrateby at least one solder joint or electrical interconnect and an alkalisilicate glass based coating at least partially covering at least onejoint or electrical interconnect surface that has a whisker pronefinish.

Another embodiment of the disclosure relates to a method for preventingthe oxidation of the surface of a solder joint or other electricalinterconnect of an electronic device. The method includes applying analkali silicate glass based coating to the surface of electricalinterconnect.

Another embodiment of the disclosure relates to a coating for reducinginteraction between a surface and the environment around the surface.The coating includes an alkali silicate glass material configured toprotect the surface from environmental corrosion due to water ormoisture. The alkali silicate glass material may or may not be dopedwith a first element to affect the radiation passing through thecoating.

Another embodiment of the disclosure relates to a coating for reducingcorrosion of a solar cell. The coating includes an alkali silicate glassmaterial configured to protect the solar cell from environmentalcorrosion due to water or moisture. The coating may or may not be dopedto protect the solar cell from UV radiation. The coating may or may notact as an anti-reflective material to improve light transmission intothe solar cell.

Another embodiment of the disclosure relates to a method for improvingmoisture durability and corrosion protection in a liquid cooling pipe.The method includes providing a first liquid in the liquid cooling pipeto clean the liquid cooling pipe, providing an alkali silicate glassmaterial such that at least a portion of an interior of the liquidcooling pipe is coated with the alkali silicate glass material, andcuring the alkali silicate glass material. The alkali silicate glassfunctions to prevent direct contact between cooling pipe and high purityliquid coolant, and therefore prevents corrosion of the cooling pipes orthe introduction of impurities to the liquid coolant.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a flow diagram illustrating the steps in a method forproducing an integrated circuit assembly according to an exemplaryembodiment.

FIG. 2 is a schematic cross-sectional view of an integrated circuitassembly produced according to the method described with respect to FIG.1 according to an exemplary embodiment.

FIG. 3 is a schematic cross-sectional view of a substrate having analkali silicate material solution provided thereon according to themethod of FIG. 1.

FIG. 4 is a schematic cross-sectional view of a substrate having analkali silicate material solution and an integrated circuit die providedthereon according to the method of FIG. 1.

FIG. 5 is a flow diagram illustrating the steps in a method forproducing a flip chip assembly according to an exemplary embodiment.

FIG. 6 is a schematic cross-sectional view of a flip chip assemblyproduced according to the method of FIG. 5 according to an exemplaryembodiment.

FIG. 7 is a schematic cross-sectional view of a flip chip assemblyillustrating the positioning of the flip chip on a substrate inaccordance with the method of FIG. 5.

FIG. 8 is a schematic cross-sectional view of a flip chip assemblyhaving an alkali silicate material solution introduced between asubstrate and a flip chip in accordance with the method of FIG. 5.

FIG. 9 is a flow diagram illustrating the steps in a method forproducing an integrated circuit assembly according to another exemplaryembodiment.

FIG. 10 is a schematic cross-sectional view of an integrated circuitassembly produced according to the method of FIG. 9 according to anexemplary embodiment.

FIG. 11 is a schematic cross-sectional view of a substrate having anintegrated circuit die and an alkali silicate material solution providedon the die according to the method of FIG. 9.

FIG. 12 is a schematic cross-sectional view of a substrate having anintegrated circuit die and a heat spreader provided thereon according tothe method of FIG. 9.

FIG. 13 is a schematic cross-sectional view illustrating the provisionof an alkali silicate solution according to the method of FIG. 9.

FIG. 14 is a schematic cross-sectional view illustrating two wafers orintegrated circuit dies coupled together using an alkali silicate glassmaterial according to an exemplary embodiment.

FIG. 15 is a flow diagram illustrating the steps in a method for makinga protected surface according to another exemplary embodiment.

FIG. 16 is a schematic cross-sectional view of a circuit producedaccording to the method of FIG. 15 according to an exemplary embodiment.

FIG. 17 is a flow diagram illustrating the steps in a method for makinga circuit according to another exemplary embodiment.

FIG. 18 is a flow diagram illustrating the steps in a method for coatinga surface according to an exemplary embodiment.

FIG. 19 is a schematic cross-sectional view of a circuit producedaccording to the method of FIG. 17 according to an exemplary embodiment.

FIG. 20 is a schematic cross-sectional view of a circuit producedaccording to the method of FIG. 17 according to another exemplaryembodiment.

FIG. 21 is a schematic cross-sectional view of a circuit producedaccording to the method of FIG. 18 according to another exemplaryembodiment.

FIG. 22 is a flow diagram illustrating the steps in a method for coatinga cooling pipe according to an exemplary embodiment.

FIG. 23 is a schematic cross-sectional view of a coated surface producedaccording to the method of FIG. 18 or FIG. 21 according to an exemplaryembodiment.

FIG. 24 is a schematic cross-sectional view of a coated surface producedaccording to the method of FIG. 18 or FIG. 21 according to anotherexemplary embodiment.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

According to an exemplary embodiment, an alkali silicate glass materialis used as a material for coupling or joining one or more electroniccomponents together (e.g., in place of more conventional adhesivematerials such as an epoxy-based die attach material), for coating theone or more electronic components, or for coating another surface. Thealkali silicate glass material is provided in the form of a liquidsolution that is provided between the surfaces of two components to bejoined together. The solution is then cured to remove the watertherefrom, which leaves a solid, moisture-impermeable material thatadheres the two surfaces together.

The alkali silicate glass material advantageously exhibits dielectricmaterial properties that are similar to or better than current adhesivematerials. In contrast to more traditional adhesive materials, however,the alkali silicate glass materials are relatively resistant to moisture(i.e., the material generally will not absorb moisture), which makessuch materials suitable for use in environments in which humidityabsorption can degrade the mechanical properties of the substrate and/ormodify its electrical characteristics.

According to an exemplary embodiment, an alkali silicate material isprovided in solution with a liquid such as deionized water, after whichthe water is removed from the solution such that the remaining alkalisilicate glass material may act to couple or join two or more electroniccomponents together. The solution may include one or more alkalisilicates, such as lithium, sodium, potassium, rubidium, cesium, orfrancium silicate materials. The solution may include a single type ofalkali silicate (e.g., lithium silicate) or more than one type (e.g., a1:1 molar ratio of lithium silicate and potassium silicate or a 1:1molar ratio of lithium silicate and sodium silicate).

Liquid alkali silicate solutions are commercially available fromcompanies such as PQ Corporation of Malvern, Pa. in a wide variety ofSiO₂ to M₂O weight ratios (this ratio may be referred to as the “Rvalue” for the solution). For example, solutions having R values ofbetween 1.00 and 3.5 or greater than 3.5 may be obtained or created bydissolving additional silica into aqueous alkali silicate solutions.These solutions may be used as-is or may be further modified (e.g., byadding deionized water to the solution, by adding particles to modifyits thermal expansion coefficient or other characteristics, etc.). Theparticular materials utilized may vary depending on the desiredapplication, material properties, and other factors according to variousexemplary embodiments.

Highly siliceous liquid alkali silicate solutions tend to air dryrapidly, are the most refractory (high melting temperature), and are themost resistant to acids and corrosion. These silica rich liquidsolutions tend to contain more water than alkaline rich solutions (persimilar viscosity), and thus undergo greater shrinkage while curing. Lowsilicate ratio, alkaline rich, solutions tend to have greaterelasticity, lower brittleness, and less shrinkage but may exhibit poorcorrosion resistance. These low ratio coatings also dry more slowlybecause their alkali content creates a greater affinity for water. Manychemically resistant cements and mortars are produced using high ratio(e.g., approximately 3.25) alkali silicate solutions. Alternatively,high alkali ratio silicate solutions may be doped with filler materialsto produce a composite that has excellent moisture and corrosionresistance as compared to the undoped material.

In order for the alkali silicate materials to become moistureimpermeable and relatively insoluble, the water must be nearlycompletely removed from the solution. The alkali silicate solutions maybe cured at relatively low temperatures (e.g., less than or equal to 160degrees Celsius, and between approximately 95 and 100 degrees Celsiusaccording to a particular exemplary embodiment) to remove the water andsolidify the material, thereby reducing residual stresses and processingcosts. According to other exemplary embodiments, curing temperatures ofgreater than 160 degrees Celsius may be utilized. According to stillother exemplary embodiments, curing temperatures of less than 100degrees Celsius may be used as desired (e.g., air drying may remove asufficient degree of moisture from the material for a particularapplication, particularly in environments where there is not substantialambient humidity). For example, according to one exemplary embodiments,an alkali silicate solution may be cured at a temperature of betweenapproximately 120 and 160 degrees Celsius for a period of betweenapproximately 120 and 240 minutes to remove the water therefrom(although it should be understood that different curing times andtemperatures may be used according to various other exemplaryembodiments). It is intended that once cured, the material willadvantageously be capable of withstanding high temperatures (e.g., up toa glass transition temperature of approximately 700 degrees Celsius).

The alkali silicate glass material may include one or more types offillers (e.g., particles) added thereto so as to provide enhancedelectrical and/or thermal conduction for the material (e.g., to allowfor electrical interconnection between the electronic components throughthe material) or alternatively to provide enhanced electrical and/orthermal insulation. The alkali silicate glass material may also includematerials therein for altering or modifying the thermal expansioncharacteristics of the material to allow it to better match the thermalexpansion characteristics of the components to which it is coupled.

For example, high thermal conductivity particles, such as, but notlimited to, diamond, aluminum nitride, beryllium oxide, or metals may beadded to the solution prior to curing to improve the thermalconductivity of the resulting alkali silicate glass material. Onepossible application for such a material may be as a material forjoining a heat spreader or similar component to another electroniccomponent to remove heat from the electronic component.

Particles may also be added to modify the thermal expansion coefficientof the material. For example, a coefficient of thermal expansion (CTE)matching filler such as glass, ceramics, metals, or polymers may beadded to the solution to modify the CTE of the final material, which mayincrease the utility of the material in applications such as underfillsfor flip-chip devices. This may improve its thermal cycle and shockloading reliability for high-temperature underfill applications (ofgreater than approximately 200 degrees Celsius). Current underfills,which are typically epoxy-based, are limited to relatively low operatingtemperatures (e.g., less than approximately 200 degrees Celsius) due tothe fact that organics may decompose at higher temperatures.

The particles may be electrically and thermally conductive (e.g.,metals, various forms of carbon, and some semiconducting ceramics)according to an exemplary embodiment. According to other exemplaryembodiments, the particles may be electrically insulating but thermallyconductive (e.g., diamond, aluminum nitride, beryllium oxide, etc.).

According to another exemplary embodiment, the alkali silicate glassmaterial may include nanoparticle modifiers, including, but not limitedto, nano calcium carbonate, nano zinc oxide and nano silicon dioxide.Aqueous alkali silicate composite solutions applied on or betweensurfaces of materials, dry to form a tough, tightly adhering inorganicbond that exhibits many desirable characteristics.

According to an exemplary embodiment, the alkali silicate glass materialmay be used as to couple or join two or more components together in anelectronics package (e.g., in a wire-bonded or flip chip integratedcircuit assembly). Various exemplary embodiments illustrating the use ofthe alkali silicate glass material in this manner are described below.

FIG. 1 is a flow diagram illustrating steps in a method 100 forproducing an integrated circuit assembly 110 according to an exemplaryembodiment. FIG. 2 is a schematic cross-sectional view of an integratedcircuit assembly 110 produced according to the method described withrespect to FIG. 1.

As shown in FIG. 2, an integrated circuit 112 is coupled or joined to asubstrate 114 (e.g., a silicon, alumina, aluminum nitride,silicon-germanium, or other type of suitable substrate) with an alkalisilicate glass material 118. In this manner, the alkali silicate glassmaterial 118 is intended to take the place of a conventional adhesive(e.g., an organic adhesive) that may be used to join the integratedcircuit 112 to the substrate 114.

In a step 102 of the method 100, the substrate 114 is prepared andprovided for assembly, after which an alkali silicate glass materialsolution 116 is provided on a top surface thereof in a step 104 asillustrated in FIG. 3. According to an exemplary embodiment, the alkalisilicate glass material solution 116 has a viscosity similar to that ofliquid water. The thickness of the solution as provided may varydepending on the application and the material used. For example, ifparticle fillers are added to the alkali silicate solution, the minimumbond thickness may be limited by the size of the particles used. Whereno particles are added, the bond thickness may be as low as desired(e.g., as low as approximately 200 nanometers). It should be understoodthat the viscosity and thickness of the solution may vary according toother exemplary embodiments.

According to an exemplary embodiment, the alkali silicate glass materialsolution 116 includes relatively small (e.g., between approximately 2and 10 micrometer diameter) electrically conductive particles (e.g.,particles of silver, tin, metal coated polymers, and/or other conductivematerials) to allow it to be used as an anisotropically conductiveadhesive (ACA) material that both mechanically bonds two surfacestogether and provides electrical connection between locations on thesurfaces. When the two horizontal surfaces are held against each other,the electrically conductive particles provide vertical electricalinterconnect between aligned electrical pads, but because the radialdistance between adjacent pads is much larger than the vertical distancebetween pads on the two surfaces, adjacent pads are not electricallyconnected. ACA's typically utilize an organic material as the adhesive,which limits their suitability in harsh environments. The use of thealkali silicate glass material 118, with appropriate electricalparticles interspersed therein, is intended to provide an ACA that isless susceptible to moisture and corrosion. This material could then beused to provide the electrical interconnect and act as a mechanicalunderfill for flip chip attached components, for example, as describedbelow with respect to FIGS. 5-8.

After the alkali silicate glass material solution 116 is provided, theintegrated circuit die 112 is provided on a top surface 117 of thealkali silicate glass material solution 116 in a step 106 as shown inFIG. 4.

In a step 108 illustrated in FIG. 2, to permanently couple or join theintegrated circuit die 112 to the substrate 114, the alkali silicateglass material solution 116 is cured at a relatively low temperature(e.g., less than or equal to approximately 160 degrees Celsius for aperiod of between approximately 120 and 240 minutes) to remove themoisture therefrom. The amount of shrinkage (if any) of the materialwill depend on the material used and other factors. For example,materials that include particles provided therein may be more resistantto shrinkage than those that do not.

FIG. 5 is a flow diagram illustrating steps in a method 200 forproducing a flip chip integrated circuit assembly 210 according toanother exemplary embodiment. FIG. 6 is a schematic cross-sectional viewof a flip chip assembly 210 produced according to the method describedwith respect to FIG. 5.

As shown in FIG. 6, an integrated circuit 112 is provided in a step 202that includes metal interconnect bumps 213 provided thereon forelectrically coupling the integrated circuit 112 to an underlyingsubstrate 214 in a flip chip configuration. As illustrated in FIG. 7,the metal bumps 213 are configured for alignment with contacts 215provided on the substrate 214, as shown in FIG. 7. As the integratedcircuit 212 is positioned on the substrate 214 in a step 204 shown inFIG. 8, the solder bumps make contact with the contacts 215 provided onthe substrate 214. According to an exemplary embodiment, the metal bumps213 and contacts 215 are formed from gold, copper, silver, tin, nickelor another metal or metal alloy.

In a step 206 shown in FIG. 8, an alkali silicate glass materialsolution 216 is provided as an underfill material for the flip chipassembly 210. The alkali silicate glass material solution 216 is thencured in a step 208 at a relatively low temperature (e.g., less than orequal to approximately 160 degrees Celsius) for an appropriate amount oftime to remove the moisture therefrom (the curing time will depend onmany factors, including, for example, the size of the device beingbonded, the material used, the temperature used, and other factors).

In a step 210, diffusion bonding is performed to further couple themetal bumps 213 to the contacts 215 at a temperature of betweenapproximately 200 and 300 degrees Celsius for a period of betweenapproximately 3 and 5 minutes (although it should be understood thatdifferent times and temperature may be used according to other exemplaryembodiments, and may vary depending on the material composition used).One advantageous feature of using the alkali silicate glass material 218as an underfill material is that once cured, such material has asoftening temperature of greater than approximately 700 degrees Celsius.Thus, during the subsequent diffusion bonding step 210, pressure ismaintained between the metal bumps 213 and the contacts 215 at elevatedtemperatures, which is intended to speed metal diffusion required forthe electrical and mechanical coupling of the components of the assembly210.

To further enhance the diffusion bonding process, the alkali silicateglass solution 216 may include particles made from metals such as tin,silver, gold, indium, gallium, copper, nickel, bismuth, and other metalsand alloys thereof. According to an exemplary embodiment, the alkalisilicate glass solution 216 may include both a “parent” metal such assilver, gold, or copper as well as a low melting temperature metal suchas tin, indium, gallium, bismuth, and other low melting temperaturemetals.

According to an exemplary embodiment, the particles (e.g., tin andsilver particles) are provided at a loading volume of betweenapproximately 10 and 70 percent. During the diffusion bonding process,the particles diffuse into the metal bumps 213 and contacts 215 to forma higher melting temperature alloy (e.g., where the metal bumps 213 andcontacts 215 are formed from gold or a gold alloy, the addition of tinand/or silver produces an alloy in the interconnect bump that has amelting temperature that is higher than that of the original particles).One advantageous feature of using the alkali silicate glass to introducetin into the diffusion bonding process is that the occurrence of metaloxidation may be reduced or eliminated (since the metal is not exposedto moisture or the ambient environment, particularly oxygen).

It should be noted that in addition to semiconductor substrates (e.g.,silicon, silicon-germanium, gallium nitrogen, gallium arsenide, zincoxide, sapphire, alumina, aluminum nitride, quartz, or other types ofsubstrates), the method described with respect to FIGS. 5-8 may also beemployed to adhere a bumped device flip chip device to a patternedindium tin oxide (ITO) coated glass material, such as that used indisplay technologies (it should be noted that other transparentconductive coatings may be used in display technologies, such ashydrogen impregnated alumina or other suitable materials). Therelatively low curing temperatures and robustness of the cured materialassociated with alkali silicate glass may advantageously improve thereliability of these devices fabricated with chip on glass assemblyprocesses.

It should also be noted that the examples described with respect toFIGS. 1-8 may also be applied to stacked die packaging assemblyprocesses that utilize through silicon vias (TSVs) in which vias withinan integrated circuit allow interconnections to be made between theactive surface of the die and the back side of the die. Advantageousfeatures of the alkali silicate glass material such as its relativelylow coefficient of thermal expansion, moisture impermeability, and lowtemperature processing make this material particularly well-suited formultiple-die applications.

According to another exemplary embodiment, the alkali silicate glassmaterial may include filler materials to enhance the thermal and/orelectrical conductivity of the material. For example, an alkali silicateglass material may include filler materials such as diamond, aluminumnitride, beryllium oxide, silicon carbide, carbon nanotubes, graphite,pyrolytic graphite, metal fillers, or other suitable filler materials ata suitable volume loading (e.g., between approximately 50 and 90percent). It should be understood that the material and volume loadingmay differ according to other exemplary embodiments depending on theparticular application and desired performance characteristics. Oneadvantageous feature of utilizing filler materials is that the resultingalkali silicate glass material may act both as a mechanical die attachmaterial as well as a thermally and/or electrically conductive dieattach material. Such filler materials may be used in conjunction withthe alkali silicate glass material in conjunction with organicsubstrates, ceramic substrates, and stacked technologies such as siliconsubstrates or other devices.

FIG. 9 is a flow diagram illustrating steps in a method 300 forproducing a wire bonded integrated circuit assembly 310 according toanother exemplary embodiment. FIG. 10 is a schematic cross-sectionalview of a wire bonded integrated circuit assembly 310 produced accordingto the method described with respect to FIG. 9. As shown in FIG. 10, theassembly 310 includes an integrated circuit die 312 provided on asubstrate 314 in accordance with a step 301. A heat spreader 316 isprovided above and coupled to the integrated circuit die 312.

As shown in FIG. 11, in a step 302, a wire bonding operation isperformed to electrically couple the integrated circuit die 312 to thesubstrate 314. Wires 313 may be made of any suitable electricallyconductive material as is well known in the art.

In a step 303, an alkali silicate glass solution 318 is provided on theactive side of the wire bonded integrated circuit 312. According to anexemplary embodiment, the alkali silicate glass solution 318 includesthermally conductive dielectric particles therein (e.g., diamond, etc.).

A heat spreader 316 is provided in contact with the alkali silicateglass solution 318 in a step 304, as shown in FIG. 12, after which asecond alkali silicate glass solution 322 is provided in a step 305 toencapsulate a portion of the assembly 310, as shown in FIG. 13. Thealkali silicate glass solutions 318 and 322 are subsequently cured toremove the moisture therefrom, which results in solid alkali silicateglass regions 320 and 324. According to other exemplary embodiments, thealkali silicate glass solutions 318 and 322 may be cured in separatecuring steps and/or the alkali silicate glass solutions 322 may bereplaced with another type of encapsulation material such as epoxy-basedmaterials.

As shown in FIG. 10, after the heat spreader 316 is attached to theintegrated circuit die 312, the outer surface of the heat spreader 316remains exposed for easy attachment to the next portion of the thermalpath, such as the package lid, a finned heat sink, a heat pipe, or thelike. The resulting device would be similar to a Quad Flatpack No Lead(QFN) or a flip chip device with an integrated heat spreader, exceptthat the heat would not have to travel through the integrated circuit togo from the active surface to the heat spreader.

According to other exemplary embodiments, the alkali silicate glassmaterials may be used in a process to adhere two surfaces together tocreate a hermetic seal. For example, such material may be used toprovide a low cost hermetic packaging method for devices that wouldotherwise use a glass frit, diffusion bonding, or welding. In additionto being lower cost, it would also be performed at much lowertemperatures, making it suitable for devices such as MEMS and otherproducts that require low temperature possessing.

According to other exemplary embodiments, the alkali silicate glassmaterial may be used to couple or attach integrated circuit waferstogether as part of a Wafer Level Packaging (WLP) assembly process, asillustrated in FIG. 14, which illustrates two wafers 410 and 420 coupledtogether using an alkali silicate glass material 430. According toanother exemplary embodiment, an alkali silicate glass material may beused to couple two integrated circuit dies together (as shown in FIG.14, the wafers may be substituted with integrated circuit dies).

As will be appreciated by those reviewing the present disclosure, theuse of alkali silicate glass materials to couple or join components ofintegrated circuit assemblies together provides various advantages overcurrently known technologies. For example, the relatively low moistureabsorption and high chemical resistance of the cured alkali silicateglass provides enhanced long term reliability when used in harsh (humid,high temperature, corrosive, etc.) environments such as that experiencedin avionics. Chemically inert particles can be added to the adhesive tomodify its thermal expansion coefficient and thermal conductivity.Particles can also be added to modify the electrical properties of thematerial and/or to facilitate diffusion bonding when an alloying elementis incorporated therein. Advantageously, the material may be cured atrelatively low temperatures, which prevents damage to the surroundingcomponents in the device.

According to various exemplary embodiments, the alkali silicate glass(ASG) composite can be used as a hermetic thermal coating and hasdielectric material properties similar to or better than conventionalcoating materials. Once cured, the material may not absorb moisture,making it suitable for use in harsh environments in which humidityabsorption can degrade mechanical properties of the coating and/ormodify its performance. The material can be cured at low temperatures(e.g., 150° C. or less), thereby reducing residual stresses andprocessing costs. Filler materials can be added to the material tocontrol the thermal expansion coefficient and give the material muchhigher thermal conductivity than can be achieved with conventionalceramic substrate materials. Coatings of ASG based materials can berobust, easily applied, and mixed with other materials to form acomposite material. The composite can be tailored to create a barrierbetween the surfaces they are in contact with and their surroundings.The ASG based coating may also act as a medium for particles that modifyan energy flux. ASG based materials can be used to create a barriercoating on a surface to prevent, or at least reduce, interactions withthe environment around it (e.g., protection against moisture).

According to various exemplary embodiments, an alkali silicate glasscomposite can be used as a coating material in numerous applicationsincluding, but not limited to, electronics packaging. The low moistureabsorption and high chemical resistance of the composite may greatlyimprove the long term reliability of the product when used in harshenvironments (e.g., humid, high temperature, corrosive, etc.) such asthose experienced by avionics. Chemically inert particles can be addedto the coating to modify the thermal expansion coefficient and thermalconductivity. Particles can also be added to modify other properties(e.g., electrical properties) of the material as desired for any givenapplication.

Referring to FIG. 15, a process flow diagram illustrates a method 500for making a protected surface according to an exemplary embodiment.Referring to FIG. 16, a schematic cross section illustrates anelectronic assembly 510 produced by method 500 according to an exemplaryembodiment. A surface 514 is provided at a step 502, for example asubstrate, circuit board, a silicon wafer, another circuit, acommunications port, an LED, a solar cell, a cooling pipe, or any othersurface for protection. A tin, cadmium, zinc, or other finish is thenapplied to surface 514 at a step 504. Surface 514 is then processes at astep 506, for example, surface 514 may have at least one component 512soldered to it. Component 512 may be any component or device capable ofmounting on a surface, for example an integrated circuit, a resistor, acapacitor, a diode, a light emitting diode (LED), an inductor, aphotovoltaic cell, etc. Soldering component 512 to surface 514 generallyproduces one or more soldering bumps or soldering joints 513. The soldermay be any type of solder, for example a lead-free solder including tin,bismuth, copper, silver, indium, zinc, antimony, any combination thereofor a leaded solder. The surface finish (e.g., tin, cadmium, zinc, etc.)of the leads being soldered and the electrical interconnect to whichthey are soldered may be prone to whiskering and or corrosion.

An alkali silicate glass (ASG) based coating 518 is applied to solderjoints, component leads, electrical interconnects, or other metallicsurfaces 513 at a step 508 to at least partially cover one or more ofthe joints and whisker and/or corrosion prone surfaces. The ASG coatingis generally configured to reduce the interaction between at least oneof these metalized surfaces 513 and the environment around the surface.For example, the ASG coating may reduce the likelihood of or prevent themetal from oxidizing and/or corroding (e.g., chemical corrosion,galvanic corrosion, etc.) and increase moisture durability of the metalsurface (e.g. solder joint, electrical interconnect, etc). The coatingmay also cover at least a portion of surface 514 and/or at least aportion of component 512 to prevent oxidation and/or increase moisturedurability. The thickness of the ASG coating may be minimized tosufficiently protect the metal surfaces while being resistant tocracking and without taking up a large amount of space.

Referring to FIG. 17, a process flow diagram illustrates a method 600for making a circuit or other electronic device according to anotherexemplary embodiment. A substrate is provided at a step 602, for examplea circuit board. An electronic device or circuit (e.g., an LED, aphotovoltaic cell, and integrated circuit, etc.) is mounted on thesubstrate at a step 604. The mounting may include soldering the circuitto the substrate.

An ASG material is doped with a first element, dopant, or filler at astep 606. The first element is generally configured to affect theradiation that impacts the coating. For example, the dopant may affectthe at least one of ultraviolet, x-ray, atomic and particle radiation,radio wave, infrared, and visible light radiation. According to variousexemplary embodiments, the first element may include nano- ormicro-particles, a chemical additive, ceramic particles, fluorescingparticles, magnetic materials, a rare-earth material (e.g., a rare earthoxide powder, a ceramic oxide include rare earth materials, etc.), alanthanide material, or an actinide material (e.g., depleted uranium).The ASG material may also be doped with additional elements includingnano- or micro-particles, a chemical additive, fluorescing particles,magnetic materials, or a rare-earth material. According to someexemplary embodiments where a fluorescing particle is used, thefluorescing particle may be a nanophosphor. According to other exemplaryembodiments, the ASG material may be doped with diamond, aluminumnitride, boron nitride, silica, and/or alumina material. According tosome exemplary embodiments, the ASG material may be doped with at least2 molar percent of the first element.

According to other exemplary embodiments, the ASG material may be dopedwith between about 3 and 25 molar percent of the first element.According to still other exemplary embodiments, the ASG material may bedoped with greater than about 25 molar percent of the first element.According to further exemplary embodiments, the ASG material may bedoped with less than about 2 molar percent of the first element if nano-or micro-particles are used.

The doped ASG material is then used to coat a surface of the circuit ata step 608. According to various exemplary embodiments, the coating isconfigured to protect the circuit from environmental corrosion oroxidation due to water or moisture. According to some exemplaryembodiments, the coating is also configured to block or absorbelectromagnetic radiation. According to other exemplary embodiments, thecoating is configured to allow electromagnetic radiation to pass throughthe coating. According to other exemplary embodiments, the coating maybe configured to retransmit electromagnetic radiation of a firstwavelength as electromagnetic radiation of a second and differentwavelength. According to other exemplary embodiments, the coating maynot be doped with a dopant or particle additive.

Referring to FIG. 18, a flow diagram illustrates the steps in a method700 for coating an existing surface according to an exemplaryembodiment. According to the various exemplary embodiments of step 606,an ASG material is doped with an element to affect the electromagneticradiation passing through the ASG material. The doped material can thenbe applied as a coating on an existing surface. For example, the ASGmaterial can be applied to a solar cell, a window, a sealing surfacebetween two materials, etc. in order to protect the surface frommoisture or water. The ASG material can also protect the surface orobject behind the surface from electromagnetic radiation. For example, acoated window may reduce the amount of ultraviolet (UV), visible, orinfrared rays that pass through as well as dissipate any heattransferred by the rays. FIGS. 19-21 provide further examples of ASGcoated circuits or surfaces. It is noted that according to otherexemplary embodiments, the ASG coating may be formulated to provideprotection without the need for doping.

Referring to FIG. 19, an electronics package 800 includes a circuit 810and a circuit 812 mounted on a substrate 814 and at least partiallyencapsulated by an ASG material 830 according to an exemplaryembodiment. The ASG material is doped with conductive particles forblocking or absorbing RF energy or radiation, at least partiallyshielding circuits 810 and 812 from radio waves. A mixed electronicsdevice having analog circuitry (e.g., circuit 812) and digital circuitry(e.g., circuit 810) can be coated with an ASG material doped with theconductive particles in a manner configured to reduce or preventcrosstalk between the circuitry and/or electromagnetic interference fromoutside package 800. When used for such applications, the dopant may bemetallic particles or magnetic particles at a quantity greater than 5volume percent up to 95.1 volume percent (for quaternary (4-particlesize) particle packing). The encapsulant (ASG material 830) can bothphysically protect the integrated circuits from moisture with a hermeticor near hermetic seal as well as reduce electromagnetic interferencebetween components or from outside sources. For example, electronicspackage 800 may reflect or block an incoming RF signal 840 or absorb anRF signal transmitted by circuit 812 in the direction of circuit 810.

According to some exemplary embodiments, ASG coating 830 may alsoinclude materials to absorb atomic particles to provide radiationhardening, for example to block x-ray, atomic radiation (gamma-ray,alpha, beta, etc.), and/or UV radiation and to reduce the likelihoodthat circuit 810 or 812 will fail due to defect formation caused by theradiation. It is noted that according to other exemplary embodiments,the ASG coating may be formulated to provide protection without the needfor doping.

Referring to FIG. 20, an electronics package 900 includes a lightemitting diode (LED) 910 mounted on a substrate 914 and at leastpartially encapsulated by an ASG material 930 according to an exemplaryembodiment. ASG material 930 may be doped with particles for spreadingor diffusing visible light radiation. ASG material 930 may be doped withfluorescing particles that at least partially absorb light from LED 910and emit or retransmit the light at a different wavelength. Certainwavelengths of light (e.g., certain colors) are difficult to generate inlight emitting diodes. Multiple colors are generally needed to producewhite light and the efficiency of generating each color may not be thesame. According to the illustrated exemplary embodiment, ASG 930 withthe integrated fluorescing particles may be excited by an LED (e.g., ahighly efficient LED) to retransmit the light at a different wavelengthwhile providing a robust coating that is generally optically clear andthat can be processed at low temperatures. It is noted that according toother exemplary embodiments, the ASG coating may be formulated toprovide protection without the need for doping. Similarly, specificbandwidths of light may be difficult to generate or filter, but ASG 930with tailored particles may be used to do this.

Referring to FIG. 21, a solar panel 1000 includes at least onephotovoltaic cell 1010 mounted on a substrate 1014 and at leastpartially coated by an ASG material 1030 according to an exemplaryembodiment. ASG material 1030 is doped with particles for absorbingspecific wavelengths of electromagnetic radiation 1040 and forretransmitting the radiation at a different wavelength. ASG material1030 may coat entire solar panels to reduce or the amount of moisture(potentially resulting in corrosion and performance degradation) onsolar panel 1000 while allowing solar radiation to pass through. ASGmaterial 1030 can be used to provide increased protection from at leastone of environmental corrosion due to water or moisture, UV light (e.g.,from the sun), and radiation protection (e.g., for use in space ormilitary applications). ASG material 1030 is doped with appropriatefillers, for example nanoparticles or chemical additives.

According to other exemplary embodiments, fluorescing particles can beadded to absorb harmful UV light and emit or retransmit useable light(e.g., visible light) to photovoltaic cell 1010 for conversion toelectrical energy. ASG coating 1030 generally has an appropriaterefractive index (e.g., by formulation or nano-particle additives) thatcan be used to create anti-reflective coatings that allow the solar cellto capture more light. ASG coatings may not significantly degrade overtime or darken from UV or other radiation exposure, can provide hermeticor near hermetic protection of the surface of photovoltaic cell 1010,and can withstand high temperatures (e.g., up to about 500-600 degreesCelsius), contrary to polymer based coatings. It is noted that accordingto other exemplary embodiments, the ASG coating may be formulated toprovide protection without the need for doping.

According to some exemplary embodiments, the coating may be chemicallytreated to have a specific refractive index or refractive index gradientbetween the substrate and air. According to other exemplary embodiments,multiple layers of glass coating having increasing or decreasingrefractive index could be used.

Referring to FIG. 22, a flow diagram illustrates the steps in a method1100 for coating a cooling pipe used to cool a device (e.g., an MRI,NMR, or other electronic device) according to an exemplary embodiment.According to various exemplary embodiments, the cooling pipe may be madeof copper or another metal. The coolant traveling in the cooling pipemay be water, another liquid, or any fluid capable of transferring heat.A liquid for cleaning is provided in the cooling pipe in order to cleanthe interior surface of the cooling pipe at a step 1102. The cleaningsolution may be a standard metal cleaner (e.g. acid, detergent, etc).After application, any residual or remaining liquid can be removed viaevaporation, via heat or blown air, or otherwise.

At least a portion of the interior of the cooling pipe is then coatedwith an ASG material that is configured to provide a dielectric barrierat a step 1104. According to one exemplary embodiment, a galvanicjunction in the cooling pipe may be coated. According to other exemplaryembodiments, the interior of the entire heat exchange area of thecooling pipe may be coated. In this embodiment, the ASG material isgenerally a highly durable material with a high silicate content or “Rvalue.” R values (e.g., SiO₂ to M₂O weight ratio when metal oxides areadded) of the ASG material at about 4.0 or higher are expected to beparticularly suitable for this application, however according to otherexemplary embodiments, the ASG material may have an R value of greaterthan about 3.5 or greater than about 3.0. For example, a molar ratio of1:1 of a binary alkali or silicate may be added along with a nano ormicroparticle dopant to achieve the desired durability. It is noted thataccording to other exemplary embodiments, the ASG coating may beformulated to provide protection without the need for doping.

The ASG coating on the interior of the pipe is then cured at a step 1106so it bonds with or adheres to the cooling pipe. The coating may becured by blowing air through the cooling pipe (e.g., drying the coating)or by heating the coating and cooling pipe. The cured coating isgenerally an insulator and configured to maintain the purity of thefluid (e.g., water, refrigerant, etc.) flowing in the cooling pipe byreducing corrosion of the cooling pipes, which lead to contamination andincreased conductivity of the cooling liquid. Therefore, the likelihoodor degree to which the fluid flowing in the cooling pipe is conductiveor contaminated may be decreased. Additionally, according to variousexemplary embodiments the ASG coating may prevent or reduce oxidation ofthe cooling pipe during handling or exposure.

The cooling pipe with the cured ASG material is provided to or installedin a cooling system at a step 1108. The cooling liquid is provided intothe cooling pipe or cooling system at a step 1110. According to variousexemplary embodiments, the cooling liquid can be water, a refrigerant,another liquid, or any other fluid capable of transferring heat.

It is noted that according to other exemplary embodiments, various stepsof method 1100 may be omitted or rearranged. According to some exemplaryembodiments, steps 1108 and 1110 may be omitted. According to otherexemplary embodiments, step 1101 may be omitted. According to stillother exemplary embodiments, steps 1102, 1108, and 1110 may be omitted.

Referring to FIG. 23, a cross section of a thin ASG based coating 1230on a metal surface 1210 (e.g., metal pipe, metal heat exchanger, etc.)for preventing or reducing the amount of oxygen contacting the metal toform a metal-oxide layer is illustrated according to an exemplaryembodiment.

Referring to FIG. 24, a cross section of a thin ASG based coating 1230around an interior of a cooling pipe 1210 (e.g., made of copper oranother metal) is illustrated according to an exemplary embodiment. Acooling fluid 1240 flows in cooling pipe 1210 and across ASG basedcoating 1230 without contacting cooling pipe 1210, preventing orreducing the likelihood of a reaction between cooling pipe 1210 andfluid 120. According to one exemplary embodiment, the cooling fluid 1240may be a highly corrosive liquid, such as liquid metal and the ASG basedcoating 1230 may prevent or reduce the likelihood that a chemical ormetallurgical interaction between solid and liquid metals occurs.According to other exemplary embodiments, the fluid 1240 may be water, arefrigerant, or another type of coolant. According to various exemplaryembodiments, the thickness of ASG layers 1230 may be optimized to reducethe likelihood of pinholes or lack of coverage (as with thick coatings)while exhibiting little cracking (as with thin coatings). According toone exemplary embodiment, the thickness of ASG coating 1230 may be about1 micron. According to another exemplary embodiment, the thickness ofASG coating 1230 may be less than or greater than 1 micron.

Various features of alkali silicate glass materials in the context ofcoatings for integrated circuit and electronics packages are describedin co-pending U.S. patent application Ser. No. 11/508,782, filed Aug.23, 2006 and co-pending U.S. patent application Ser. No. 11/959,225,filed Dec. 18, 2007, the entire disclosures of which are incorporatedherein by reference.

According to various exemplary embodiments, the coating may be a coatingdescribed in U.S. patent application Ser. No. 11/508,782, filed on Aug.23, 2006, and entitled “Integrated Circuit Protection and RuggedizationCoatings and Methods,” U.S. patent application Ser. No. 11/784,158,filed on Apr. 5, 2007 and entitled “Hermetic Seal and Hermetic ConnectorReinforcement and Repair with Low temperature Glass Coatings,” U.S.patent application Ser. No. 11/732,982, filed on Apr. 5, 2007, andentitled “A Method for Providing Near-Hermetically Coated IntegratedCircuit Assemblies,” U.S. patent application Ser. No. 11/732,981, filedon Apr. 5, 2007, and entitled “A Method for Providing Near-HermeticallyCoated, Thermally Protected Integrated Circuit Assemblies,” U.S. patentapplication Ser. No. 11/784,932, filed on Apr. 10, 2007, and entitled“Integrated Circuit Tampering Protection and Reverse EngineeringPrevention Coatings and Methods,” U.S. patent application Ser. No.11/959,225, filed on Dec. 18, 2007, and entitled “Adhesive ApplicationsUsing Alkali Silicate Glass for Electronics,” U.S. patent applicationSer. No. 11/959,225, filed Dec. 18, 2007, and entitled “AdhesiveApplications for Using Alkali Silicate Glass for Electronics,” and U.S.application Ser. No. 12/116,126, filed on May 6, 2008, and entitled“System and Method for a Substrate with Internal Pumped Liquid metal forthermal Spreading and Cooling,” each of which is herein incorporated byreference in its entirety.

As utilized herein, the terms “approximately,” “about,” “substantially”,and similar terms are intended to have a broad meaning in harmony withthe common and accepted usage by those of ordinary skill in the art towhich the subject matter of this disclosure pertains. It should beunderstood by those of skill in the art who review this disclosure thatthese terms are intended to allow a description of certain featuresdescribed and claimed without restricting the scope of these features tothe precise numerical ranges provided. Accordingly, these terms shouldbe interpreted as indicating that insubstantial or inconsequentialmodifications or alterations of the subject matter described and claimedare considered to be within the scope of the invention as recited in theappended claims.

It should be noted that references to relative positions (e.g., “top”and “bottom”) in this description are merely used to identify variouselements as are oriented in the FIGURES. It should be recognized thatthe orientation of particular components may vary greatly depending onthe application in which they are used.

For the purpose of this disclosure, the term “coupled” means the joiningof two members directly or indirectly to one another. Such joining maybe stationary in nature or moveable in nature. Such joining may beachieved with the two members or the two members and any additionalintermediate members being integrally formed as a single unitary bodywith one another or with the two members or the two members and anyadditional intermediate members being attached to one another. Suchjoining may be permanent in nature or may be removable or releasable innature.

It is also important to note that the construction and arrangement ofthe components as shown in the various exemplary embodiments isillustrative only. Although only a few embodiments have been describedin detail in this disclosure, those skilled in the art who review thisdisclosure will readily appreciate that many modifications are possible(e.g., variations in sizes, dimensions, structures, shapes andproportions of the various elements, values of parameters, mountingarrangements, use of materials, colors, orientations, etc.) withoutmaterially departing from the novel teachings and advantages of thesubject matter recited in the claims. For example, elements shown asintegrally formed may be constructed of multiple parts or elements, theposition of elements may be reversed or otherwise varied, and the natureor number of discrete elements or positions may be altered or varied.The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. Other substitutions,modifications, changes and omissions may be made in the design,operating conditions and arrangement of the various exemplaryembodiments without departing from the scope of the present inventionsas expressed in the appended claims.

1. A surface, comprising: metal that is exposed to an externalenvironment, at least a portion of the metal having a finish that isprone to whiskering; and an alkali silicate glass based coating at leastpartially covering the metal.
 2. The surface of claim 1, wherein thefinish is tin, cadmium, or zinc.
 3. The surface of claim 1, wherein thesurface is a part of an electronic assembly comprising: an electronicdevice mounted on a substrate by at least one solder joint or otherelectrical interconnect; an alkali silicate glass based coating at leastpartially covering at least one solder joint or electrical interconnect.4. The electronic assembly of claim 3, wherein the metal within theassembly is at least partially composed of tin, cadmium, or zinc.
 5. Theelectronic assembly of claim 3, wherein the coating covers at least aportion of the metal within the electronics assembly.
 6. The electronicassembly of claim 3, wherein the electronic device is at least one of anintegrated circuit, a resistor, a capacitor, a diode, a light emittingdiode, an inductor, and a photovoltaic cell.
 7. The electronic assemblyof claim 3, wherein the coating is configured to reduce interactionbetween the solder joint or electrical interconnect and an environmentaround the surface, whereby the metal is prevented from oxidizing,whiskering, or corroding.
 8. A method for preventing the oxidation of asolder joint or electrical interconnect of an electronic device,comprising: applying an alkali silicate glass based coating to thesoldering joint or electrical interconnect.
 9. A coating for reducinginteraction between a surface and the environment around the surface,comprising: an alkali silicate glass material configured to protect thesurface from environmental corrosion due to water or moisture.
 10. Thecoating of claim 9, wherein the alkali silicate glass material is dopedwith a first element to affect radiation passing through the coating.11. The coating of claim 10, wherein the radiation is at least one ofultraviolet, x-ray, gamma ray, and radio wave radiation.
 12. The coatingof claim 10, wherein the first element comprises at least one ofnanoparticles, a chemical additive, ceramic particles, fluorescingparticles, magnetic materials, rare earth materials, lanthanidematerials, and actinide materials.
 13. The coating of claim 12, whereinthe surface is a surface of a solar cell, the coating is at leastpartially transparent.
 14. The coating of claim 12, wherein fluorescingparticles block ultraviolet light and retransmit usable light to a solarcell.
 15. The coating of claim 12, wherein the surface is a surface of alight emitting diode, the coating is at least partially transparent, andfluorescing particles absorb light from the light emitting diode andretransmit light at a different wavelength.
 16. The coating of claim 15,wherein the fluorescing particles are nanophosphors.
 17. The coating ofclaim 9, wherein the surface is a surface of a solar cell, a window, asealing surface between two materials, a light emitting diode, or anelectronic device.
 18. A coating for reducing corrosion of a solar cell,comprising: an alkali silicate glass material configured to protect thesolar cell from environmental corrosion due to water or moisture. 19.The coating of claim 18, wherein the alkali silicate glass material isconfigured to provide protection to the solar cell from ultravioletradiation.
 20. The coating of claim 19, wherein the alkali silicateglass material is doped with fluorescing rare earth oxide nanoparticlesthat absorb UV radiation and emit or fluoresce a visible wavelength thatthe solar cell can convert into electrical energy.
 21. The coating ofclaim 18, wherein the alkali silicate glass material is ananti-reflective material configured to improve light transmission intothe solar cell.
 22. The coating of claim 21, wherein a refractive indexof the alkali silicate glass material may be modified by a dopant or bymodifying the alkali silicate glass chemistry.
 23. The coating of claim21, further comprising multiple layers of alkali silicate glassmaterial, each layer of alkali silicate glass material having adifferent refractive index.
 24. A method for improving moisturedurability in a liquid cooling pipe, comprising: providing a firstliquid in the liquid cooling pipe to clean the liquid cooling pipe;providing an alkali silicate glass material such that at least a portionof an interior of the liquid cooling pipe is coated with the alkalisilicate glass material; and curing the alkali silicate glass material.25. The method of claim 24, wherein the curing of the alkali silicateglass material is performed by blowing air across the alkali silicateglass material or by applying heat to the alkali silicate glassmaterial.
 26. The method of claim 24, wherein the alkali silicate glassmaterial coats a galvanic junction in the liquid cooling pipe.
 27. Themethod of claim 24, wherein the liquid cooling pipe is installed to coola magnetic resonance imaging device, a nuclear magnetic resonancedevice, a circuit or collection of circuits, or a power supply.
 28. Themethod of claim 24, wherein the alkali silicate glass material has ahigh enough chemical durability that the cooling liquid remains highpurity and free of contamination otherwise caused by corrosion of thecooling pipes.
 29. The method of claim 24, wherein the alkali silicateglass material prevents oxidation or corrosion of the liquid coolingpipe.
 30. The method of claim 24, wherein the coolant is water.
 31. Themethod of claim 24, wherein the liquid cooling pipe is composed ofmetal.
 32. The method of claim 31, wherein the metal is copper.